1. Field of the Invention
The present invention relates to transfer, under a clean environment, of various articles to be processed such as a semiconductor wafer in a manufacturing process of a semiconductor, an electronic part related product, an optical disk or the like, and more particularly to a clean box that makes it possible to transfer the articles among various processing devices in a clean condition without any contaminated substance, a clean transfer method and a clean transfer system using such a clean box.
2. Related Background Art
Recently, in a manufacturing process that needs a high level clean environment such as a semiconductor device manufacturing process, a method such as a mini-environment or a local clean space for keeping only the peripheral environment of a product under a clean condition without making the entire factory into a clean room state has been employed. Simply stating, this means that only an interior of each processing device in the manufacturing process is kept under a clean environment, and the transfer and the deposit of the articles to be processed is performed among the respective processing devices (clean devices) by using containers whose interior is kept clean (which will be referred to as clean boxes).
An example of such a local clean space system in the semiconductor manufacturing process will now be described with reference to FIG. 1 that illustrates an embodiment of the present invention. FIG. 1 shows a condition that a clean box 40 is mounted on a semiconductor wafer processing apparatus 10 as the local clean space (i.e., clean device).
The semiconductor wafer processing apparatus 10 is composed of an apparatus body 30 and a load port 20 for loading into the apparatus from the outside of the apparatus a semiconductor wafer that is an article to be processed by the apparatus body 30. FIG. 1 shows the apparatus body 30 on the left side and the load port on the right side of a straight line A. These load port 20 and the apparatus body 30 make the local clean space within the semiconductor wafer processing apparatus 10 together.
In such a local clean space system, in order to transfer the semiconductor wafer while keeping the clean condition among different processing devices, the clean box as a container whose interior is kept clean is used. FIG. 1 shows a condition that the bottom open type clean box 40 is mounted on the load port 20. The clean box 40 is composed of a box body 41 and a lid 42. The lid 42 is removed downwardly and the wafer in the interior is taken out to be loaded on the processing device under the condition that the clean box 40 is laid on the load port 20.
In the conventional clean box, the fixture of the lid to the box body has been carried out by a mechanical lock mechanism. For instance, a lock mechanism provided on the lid member and composed of a movable claw made of metal and a rotary cam member for moving the movable claw between a lock position where the movable claw projects by a predetermined amount from the outer periphery of the lid and a release position where the movable claw is retracted from the outer periphery of the of the lid, is used. In the case where the lid is to be fixed to the box body, the rotary cam member is rotated to thereby bring the movable claw to the lock position and the movable claw is engaged with a hole formed in the box body in this position so that the lid is locked to the box body. Such a lock mechanism of the clean box is operated by causing the above-described cam member to rotate by an opening/closing device provided in the load port under the condition that the clean box is mounted on the load port, to thereby perform the locking/releasing operation of the lid to/from the box body.
In order to keep the interior of the clean box clean, it is necessary to keep a sealed condition against the outside. Accordingly, a sealing means such as an O-ring for sealing the interface between the lid and the box body is provided. However, the above-described mechanical lock mechanism that has been used in the conventional clean box may impart a pressure of only several N""s (Newton) at the largest so that the O-ring is not sufficiently deformed. For this reason, it is impossible to prevent dust or any other organic or inorganic substance from entering the interior, and it is impossible to maintain the clean space.
Also, in order to prevent the natural oxidation of the semiconductor wafer during the process waiting period, the interior air within the clean box is replaced with non-oxidizing gas such as nitrogen N2 and inert gas, in some cases. However, the sealing force is small in the conventional mechanical lid lock mechanism, and therefore it is impossible to maintain the replacement condition of the non-oxidizing gas.
An object of the present invention is to provide a bottom removal type clean box that is high in sealing property in comparison with a mechanical lock mechanism, and a transfer method and system using such a clean box.
In order to attain the above-mentioned object, a clean box according to a first aspect of the present invention has a structure comprising: a box body having an opening in a bottom; a lid member for closing the opening; an annular groove formed so as to surround the opening on at least one of the box body and the lid member to define a suction space sealed between the lid member and the box body under the condition that the lid member is mounted on the box body; and an intake/exhaust port for allowing vacuum exhaust/release of the annular groove from the outside.
The above-described annular groove may be formed on either box body side or lid member side or on both sides. In any case, in order to apply the present invention to a practical case, it is preferable that the periphery of the opening of the box body is in the form of a flanged shape and the annular groove is formed on the flange or on a portion of the lid member confronting the flange of the box body. In order to effect sealing, a sealing member such as an O-ring is provided along the groove. The clean box according to another aspect of the present invention to be described later also has the same structure with respect to the annular groove.
In this clean box, provision of the mechanical latch for preventing the lid member from falling apart from the box body is preferable, since even if the vacuum suction is damaged due to some reason during the transfer of the box, there is no fear that the lid member falls down. It is preferable that the mechanical latch has a mechanism for opening/closing the latch from the outside.
Also, as described above, if the semiconductor wafer is exposed in the air, an oxide film is naturally grown. This is undesirable. In order to prevent this, the gas within the clean box is replaced with the non-oxidizing gas such as nitrogen or inert gas. In accordance with this, a valve may be provided in the clean box according to the present invention for allowing the gas to be discharged or introduced for the replacement of the gas within the interior of the clean box.
It is preferable that the valve for replacement of gas in the interior of the clean box is composed of a gas input valve having a valve body for introducing the non-oxidizing gas into the interior of the clean box and a gas output valve having a valve body for discharging the gas in the clean box to the outside.
In a preferred mode of the clean box according to the present invention, an annular groove intake/exhaust port and the valves for gas replacement (gas input valve and gas output valve) are provided on the same single side surface of the clean box body. Thus, since the access directions for the vacuum discharge of the above-described annular groove and the various arrangements for replacement of the gas in the clean box, provided on the load port of a clean device such as a semiconductor wafer processing apparatus which receives clean box become the same, it is possible to simplify the structure of the load port. For example, the above-described various arrangements may be formed as a single unit that allows the unit to access to the clean box by one operation.
A clean transfer system in which a clean box according to the first aspect of the present invention is employed, is structured as described below. That is, a clean transfer system comprising:
a clean box comprising: a box body having an opening in a bottom; a lid member for closing the opening; an annular groove formed so as to surround the opening on at least one of the box body and the lid member to define a suction space sealed between the lid member and the box body under the condition that the lid member is mounted on the box body; and an intake/exhaust port for allowing vacuum exhaust/release of the annular groove from the outside, and
a load port of a clean device whose interior is kept under a clean environment and having a box lid opening/closing mechanism for opening/closing the lid member of the clean box,
wherein the clean box is disposed with the lid member facing downward so that the lid member and the box lid opening/closing mechanism on the load port are aligned to confront with each other, and
the load port has a means for vacuum discharging/vacuum releasing the suction space through the intake/exhaust port of the clean box.
In a preferred mode of the clean transfer system, a valve for allowing the gas replacement in the interior of the clean box is provided in the above-described clean box.
It is preferable that the valve for replacement of gas in the interior of the clean box is composed of a gas input valve having a valve body for introducing the non-oxidizing gas into the interior of the clean box and a gas output valve having a valve body for discharging the gas in the clean box to the outside. In this case, arrangements for gas replacement in cooperation with these valves, i.e., a gas feed device in cooperation with the gas input valve and a gas discharge device in cooperation with the gas output valve are provided on the load port.
In this case, it is preferable that an annular groove intake/exhaust ports and valves for gas replacement (gas input valve and gas output valve) be provided on the same single side surface of the clean box body, and means for vacuum exhaust/release of the above-described annular groove or various arrangements for gas replacement in the clean box in cooperation with the valves are constituted into a single unit so that the clean box may be accessed by one operation.
A clean box according to a second aspect of the present invention has a structure comprising: a box body having an opening in one surface thereof; a lid member for closing the opening; an annular groove formed so as to surround the opening on at least one of the box body and the lid member to define a suction space sealed between the lid member and the box body under the condition that the lid member is mounted on the box body; and an intake/exhaust port for allowing vacuum exhaust/release of the annular groove from the outside, formed on the lid member.
Thus, the annular groove is provided between the box body and the lid member to define the suction space to thereby vacuum discharge the annular groove so that the lid member is strongly absorbed to the box body by the pressure difference between the annular groove and the outside. Thus, it is possible to air-tightly seal the interface between the lid member and the box body with a uniform and strong force in comparison with the mechanical lock mechanism. In addition, since the annular groove intake/exhaust port for vacuum exhaust/release is provided on the lid member side, upon setting the clean box on the load port of the clean device such as a semiconductor processing apparatus, it is sufficient that the alignment between the clean box and the load port is performed only on the surface on the lid side.
In this clean box, the vacuum suction between the lid member and the box body is realized by exhausting from the outside the air in the suction space of the annular groove thus produced. It is possible to constitute the intake/exhaust port for vacuum exhaust/release of the annular groove from the outside as a passage passing through the lid member to open to the outside (on the surface of the lid member confronting the outside) and a valve mechanism for opening/closing the passage. A mechanism for opening/closing the valve is provided on the load port side.
Also, according to this second aspect of the invention, in the same manner as in the above-described first aspect of the invention, the valves for allowing the replacement of the gas within the clean box may be provided. It is preferable that these valves be provided on the lid member.
It is preferable that these valves be composed of a gas input valve comprising a valve for introducing the non-oxidizing gas into the interior of the clean box and a gas output valve comprising a valve for discharging the gas in the clean box to the outside.
The valve is also provided on the lid member. So, if only the alignment between the lid side of the clean box and the load port is performed, the alignment between the valve and the gas replacement device that works in corporation with the valve on the side of the load port is also attained. In this case, a mechanism performing the introduction/discharge of the gas from/to the interior of the box may be provided integrally with the box lid opening/closing mechanism.
In the case where the clean transfer system is constituted by using the clean box in accordance with the second aspect of this invention, it is possible for all the various mechanisms of the load port to access the clean box from one direction (i.e., from the side of the lid member). In this case, the lid opening/closing mechanism (including the mechanism for performing the vacuum exhaust/release of the annular groove) of the clean box and the mechanism for gas replacement of the clean box (if the clean box has the gas replacement valves) are both provided in the one single elevator mechanism to thereby simplify the structure. Also, in the clean transfer system using this clean box, it is preferable that a means for performing the alignment between the lid member of the clean box and the load port be provided. It is possible to constitute this alignment means as, for example, a combination of a plurality of positioning pins provided on the load port and the holes engaged with the pins on the lid member of the clean box.
A clean transfer method according to the present invention uses the clean box according to the present invention. That is, the clean box comprises: a box body having an opening in a bottom; a lid member for closing the opening; an annular groove formed so as to surround the opening on at least one of the box body and the lid member to define a suction space sealed between the lid member and the box body under the condition that the lid member is mounted on the box body; and an intake/exhaust port for performing vacuum exhaust/release of the annular groove from the outside, and the clean transfer method comprises the steps of:
setting the clean box, sucked by vacuum exhausting the annular groove, on a load port of a clean device whose interior is kept under a clean environment and having a box lid opening/closing mechanism for opening/closing the lid member of the clean box, so that the lid member and the box lid opening/closing mechanism on the load port are aligned to confront with each other with the lid member facing downwardly;
releasing vacuum in the suction space through the intake/exhaust port by a mechanism for releasing the vacuum provided in the load port to thereby open the lid member; and
picking up an article to be transferred within the clean box and moving the article to the clean device.
Also, after the article to be transferred that has been subjected to the process in the clean device is returned to the interior of the clean box, the lid member of the clean box is closed by the above-described box lid opening/closing mechanism. Then, the above-described suction space is evacuated through the above-described intake/exhaust mechanism by the vacuum exhaust mechanism provided in the load port so that the lid member and the box body are sucked to each other. It is preferable that the mechanism for releasing the vacuum and the vacuum exhaust mechanism are formed into one unit.
In the clean transfer method according to the present invention, in the case where the clean box has the mechanical latch, the box lid opening/closing mechanism releases the mechanical latch before the release of the vacuum in the suction space. Also, after the article to be transferred that has been subjected to the process in the clean device is returned to the interior of the clean box, the above-described suction space is evacuated to suck the lid member and the box body together. Thereafter, the mechanical latch is effected.
In the above-described clean transfer method, in the case where the clean box has the valve allowing the gas replacement in the interior of the clean box and the gas in the clean box is replaced with the non-oxidizing gas, the article to be transferred that has been subjected to the process in the clean device is returned to the interior of the clean box, the lid member of the clean box is closed, and the above-described suction space is exhausted to thereby suck the lid member and the box body together. Thereafter, the replacement of the gas in the interior of the clean box is carried out through the valve.
A clean transfer method according to another aspect of the present invention is characterized in that: the clean transfer method uses a clean box comprising: a box body having an opening in a bottom; a lid member for closing the opening; an annular groove formed so as to surround the opening on at least one of the box body and the lid member to define a suction space sealed between the lid member and the box body under the condition that the lid member is mounted on the box body; and an intake/exhaust port for performing vacuum exhaust/release of the annular groove from the outside, formed on the lid member, and that: the clean transfer method comprises the steps of:
setting the clean box, sucked by vacuum exhausting the annular groove, on a load port of a clean device whose interior is kept under a clean environment and having a box lid opening/closing mechanism for opening/closing the lid member of the clean box, so that the lid member and the box lid opening/closing mechanism on the load port are aligned to confront with each other;
releasing vacuum in the suction space by a box lid opening/closing mechanism of the load port through the intake/exhaust port provided on the lid member of the clean box to thereby open the lid member; and
picking up an article to be transferred within the clean box and moving the article to the clean device.
Also, in this clean transfer method; the article to be transferred that has been subjected to the process in the clean device is returned to the interior of the clean box, the above-described box lid opening/closing mechanism closes the lid member of the clean box, and the above-described suction space is exhausted or evacuated through the above-described intake/exhaust mechanism to thereby suck the lid member and the box body together.
In the case where the clean box has the mechanical latch, the box lid opening/closing mechanism releases the mechanical latch before the release of the vacuum in the suction space. Also, after the article to be transferred that has been subjected to the process in the clean device is returned to the interior of the clean box, the above-described suction space is evacuated to suck the lid member and the box body together. Thereafter, the mechanical latch is effected.
Also, in this clean transfer method, in the case where the clean box has the valve that allows the gas replacement in the interior of the clean box and the gas in the clean box is replaced with the non-oxidizing gas, the article to be transferred that has been subjected to the process in the clean device is returned to the interior of the clean box, the lid member of the clean box is closed, and the above-described suction space is discharged through the above-described intake/exhaust mechanism to thereby suck the lid member and the box body together. Thereafter, the gas in the interior of the clean box is replaced through the valve.